The present invention relates to a gearing, in particular coaxial gearing, hollow-shaft gearing, hypoid gearing, axial gearing or linear gearing, having a drive input element, an element and a drive output element.
Conventional gearings of diverse forms and designs are known and available commercially.
Use is made commercially substantially of three different gearing technologies. Firstly, commercially, planetary gear sets are known in which, for example within a ring gear, one or more planet gears are provided coaxially by means of a usually centrally arranged sun gear for transmitting a torque to a planet gear carrier or drive output element.
In such epicyclic or planetary gear sets, high transmission speeds are not possible, and it is not possible for high torques to be transmitted with small hollow shaft diameters. Furthermore, gearings of said type are afflicted with low strength and a low level of robustness, with said gearings having a low overload capability.
It is also disadvantageous that, in particular in the case of high drive-input-side rotational speeds, a transmission ratio is restricted.
Eccentric gearings are also known, in which, usually, a planet gear is provided within a toothed ring gear in order to transmit torques and to produce transmission ratios.
A disadvantage of eccentric gearings is that said gearings require high release forces and very large bearings, in particular in the case of hollow-shaft designs, and are suitable only for hollow-shaft designs with relatively small diameters. Here, too, said eccentric gearings have low overload capabilities and low levels of robustness.
Furthermore, the transmission ratio ranges are restricted to approximately i=30 to i=100, with this being the case only at low drive input rotational speeds. At higher drive input rotational speeds, eccentric gearings of said type have a high level of wear and therefore have a short service life, which is undesirable.
Furthermore, such eccentric gearings have high friction losses and therefore low levels of efficiency, since clutches or the like are connected to eccentric gearings in order to convert the eccentric drive movement into a central movement. The efficiency of the eccentric gearing is therefore very low.
At high rotational speeds in particular, considerable vibration problems occur, which are likewise undesirable.
Also known are harmonic drive gearings which may duly also be designed as hollow-shaft gearings, with a so-called flex spline being arranged between a usually oval drive input element and an internally toothed ring gear, which flex spline is of soft and flexible design and transmits the corresponding torque between the drive input and the ring gear and permits a transmission ratio.
The so-called flex spline is subjected to permanent loads and often fails under high torques. Furthermore, the flex spline is not capable of withstanding overloads and often breaks at excessively high torques. The harmonic drive gearing also has a poor efficiency and low torsional stiffness.